An airframe of an aircraft typically includes a variety of structural elements and structural subassemblies. Individual subassemblies may be separately fabricated in parallel with one another. The completed subassemblies may be assembled to form the airframe. During assembly, the subassemblies may be brought together and aligned with one another. The mating surfaces of the subassemblies may be interconnected to one another using mechanical fasteners.
When individual subassemblies are manufactured by the same manufacturer in the same general location or facility, the individual subassemblies can be closely monitored during fabrication such that adjustments can be made to ensure that the subassemblies will align with one another when assembled without excessive gaps between the mating surfaces. In this regard, subassemblies that are manufactured in the same facility may be formed using commonly-designed or commonly-manufactured tooling to ensure alignment of the mating surfaces without excessive gaps.
However, when subassemblies are manufactured in separate facilities or at different locations using separately-designed and/or separately-manufactured tooling, the mating surfaces may not fit up to one another without the occurrence of gaps between the mating surfaces. Where gaps occur, shimming may be required to fill such gaps prior to joining the subassemblies using mechanical fasteners. Unfortunately, the shimming of gaps between mating surfaces is a time-consuming process that requires measuring the thickness of each gap and the length and width dimensions of the shim required to fill the gap. Each shim must then be fabricated such as by machining or forming the shim in a manner such that the completed shim matches the required shim dimensions.
Occasionally, contoured shims must be fabricated for locations where the gap between two surfaces varies at different locations within the gap. The contoured shim must be fabricated in the required thicknesses at each location of the shim. The shim must also be formed with the required length and width dimensions to match the gap wherein the shim will be installed. The shim may additionally be subjected to inspection and buyoff. The shim must then be installed during fastener installation which may add complexity to the fastener installation process. For the mating of subassemblies having a variety of mating surfaces, the process of measuring the gap thicknesses and the length and width dimensions for each shim, fabricating the shim, inspecting the shim, and then installing the shim may be repeated numerous times. For a large airframe having multiple subassemblies and structural elements that must mate with one another, the process of shim fabrication and installation can significantly add to the production flow time.
As can be seen, there exists a need in the art for a system and method for joining structural elements or subassemblies without the need for shimming between the mating surfaces of the structural elements or subassemblies.